TH and Parkinson disease: Thirdly, in a sub-acute MPTP model of PD with daily subcutaneous injection of MPTP for 6 days, mouse midbrains displayed sustained upregulation of G6PD, gp91phox, and Iba1 as well as reduction in TH level at 3 and 7 months after the last MPTP injection (Fig. 1e, f).